The present invention relates to power tools for drilling holes in a workpiece and, more particularly, to a peck drilling tool for gradually drilling such holes.
Over the years, many different types of drilling tools have been made for drilling holes in workpieces. The type of drilling tool selected for a particular job depends, of course, on several factors. In the aerospace industry, for example, highly specialized power drilling tools have been developed to rapidly and accurately drill holes in panels and other airframe structures to facilitate assembly of the aircraft. In these applications, various types of materials comprising the panels are encountered. These materials often are constructed from lightweight alloys in view of the need to have the aircraft weigh as little as possible after it has been assembled
When it is necessary to drill holes in lightweight materials, such as aluminum or various types of composites, special care must be taken to ensure that the hole is carefully and properly drilled. It has been discovered, for example, that the use of a conventional drilling tool to bore directly through the material in one pass does not produce an accurate or consistent sized hole in many instances. These problems result primarily from the relatively large amounts of heat and high frictional forces that are developed during a single pass of the drill bit through the material, especially when thicker materials are involved.
Various solutions have been implemented to overcome the problems associated with the continuous single pass drilling tools noted above. One solution has been the development of the so-called peck drilling tool. The peck drilling tool is usually a pneumatically or hydraulically operated power tool in which the drill bit is advanced into the material a short distance and then withdrawn. This cycle of advancing and then withdrawing the drill bit is repeated until the drill bit eventually bores a hole completely through the material. In each cycle of the tool, the depth of penetration of the drill bit may be varied as desired, provided that it is less than the thickness of the material itself for each cycle. Depending upon the type of material involved, the size of the hole to be drilled and other factors, many or only a few cycles will be required to bore the hole. Peck drilling tools of this type have been found to produce an accurate and consistent sized hole in most materials.
While known peck drilling tools have proven to be successful for their intended purpose, they are not without certain disadvantages. One drawback is the size and complexity of the tool. The highly specialized nature of the tool also makes it relatively expensive to manufacture and purchase. Moreover, it has not been possible to transform the conventional, single pass drilling tools into peck drilling tools. As a result, it is usually necessary to purchase an entirely new tool when peck drilling capabilities are required.
Accordingly, there has existed a definite need for a new and improved peck drilling tool that is smaller in size and less complicated than existing peck drilling tools. There also has existed a definite need for a mechanism to convert the conventional, single pass drilling tools into peck drilling tools. The present invention satisfies these needs and provides further related advantages.